Make progress in incremental marking if scavenge is delaying mark-sweep.

src/spaces.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1216 matching lines @@
   Address old_top = allocation_info_.top;
   Address new_top = old_top + size_in_bytes;
   Address high = to_space_.page_high();
   if (allocation_info_.limit < high) {
     // Incremental marking has lowered the limit to get a
     // chance to do a step.
     allocation_info_.limit = Min(
         allocation_info_.limit + inline_allocation_limit_step_,
         high);
     int bytes_allocated = static_cast<int>(new_top - top_on_previous_step_);
-    heap()->incremental_marking()->Step(bytes_allocated);
+    heap()->incremental_marking()->Step(
+        bytes_allocated, IncrementalMarking::GC_VIA_STACK_GUARD);
     top_on_previous_step_ = new_top;
     return AllocateRaw(size_in_bytes);
   } else if (AddFreshPage()) {
     // Switched to new page. Try allocating again.
     int bytes_allocated = static_cast<int>(old_top - top_on_previous_step_);
-    heap()->incremental_marking()->Step(bytes_allocated);
+    heap()->incremental_marking()->Step(
+        bytes_allocated, IncrementalMarking::GC_VIA_STACK_GUARD);
     top_on_previous_step_ = to_space_.page_low();
     return AllocateRaw(size_in_bytes);
   } else {
     return Failure::RetryAfterGC();
   }
 }
 
 
 #ifdef DEBUG
 // We do not use the SemiSpaceIterator because verification doesn't assume
@@ skipping 1596 matching lines @@
     object->ShortPrint();
     PrintF("\n");
   }
   printf(" --------------------------------------\n");
   printf(" Marked: %x, LiveCount: %x\n", mark_size, LiveBytes());
 }
 
 #endif  // DEBUG
 
 } }  // namespace v8::internal